In recent years, vigorous research activity has been conducted to identify and synthesize suitable chelating agents for metal ions and particularly trivalent metal ions such as the group 13 metals and the lanthanides, for use in nuclear medicine. This is because of the deleterious effects of these metals (e.g. concern over aluminum neurotoxicity) and their burgeoning use in vivo as diagnostic probes. For example, gallium and indium radionuclides are used in radiopharmaceuticals. Further, the physical properties of the lanthanides are exploited as luminescent, EPR, and NMR shift probes. They also have widespread application as magnetic resonance imaging contrast agents. Similarities in oxophilicity (e.g. Al(III), Ln(III) and ionic radii (e.g. In(III), Ln(III) do not necessarily result in a complementary chemistry for the respective group 13 and lanthanide ions.
The following three patents disclose transition metal complexes and functionalized tripodal ligands for imaging applications:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 4,999,443 Bertleff et al. March 12, 1991 5,405,601 Dunn et al. April 11, 1995 5,565,184 Dunn et al. October 15, 1996 ______________________________________